Next week's Senate hearing on the Iowa egg recalls could shed new light on the confusing separation of powers between the FDA and the USDA.

As lawmakers prepare for hearings into the largest egg recall in U.S. history, food safety advocates say the congressional probe could give momentum to a long-delayed measure that would enhance the power of the Food and Drug Administration.

If passed, say policymakers, the FDA Food Safety Modernization Act could be the first major step toward streamlining the often unwieldy food safety system.

Lawmakers will grapple with the circumstances surrounding the recall this week in a congressional probe of the outbreak of salmonella enteritidis that has sickened more than 1,500 people.

Most policymakers and food safety experts agree the regulatory system is broken. The upcoming hearing, scheduled for Tuesday and expected to attract significant media attention, could speed passage of the Senate bill, which has languished for months. Or the bill could be sidelined by a legislative calendar already compressed by the pending midterm elections.

The House Energy and Commerce Subcommittee on Health has invited the owners of the two Iowa megafarms implicated in the recall of 550 million eggs to testify at the proceeding. It also has requested records from the USDA and FDA in an effort to untangle what is a classic illustration of food safety regulation at its most confusing.

The USDA regulates the quality of eggs still in their shells; it also inspects liquid, dried and frozen egg products. The FDA is responsible for the safety of eggs still in their shells, but until recently it could intervene only after problems became evident. So neither agency was proactive about examining the production facilities operated by Wright County Egg and Hillandale Farms of Iowa, where federal inspectors recently found giant manure piles, rodents and maggots.

Last week, congressional investigators released records showing Wright County Egg received a positive test result for salmonella enteritidis more than a week before the FDA pressed the company to launch a recall. The records also indicated that from 2008 to 2010, testing at the Iowa farm found 426 positive tests for some strains of salmonella, including 73 samples potentially positive for salmonella enteritidis.

The Justice Department and FDA have launched a criminal investigation into the distribution of the contaminated eggs.

In what FDA Commissioner Margaret Hamburg recently termed an "unfortunate irony," new FDA rules governing egg safety went into effect July 9, too late to prevent the current salmonella outbreak. The rules set standards for facility cleanliness, testing for salmonella and record-keeping. But it doesn't bridge the gap over the split oversight of eggs.

Though the Senate bill also remains mum on reconciling such divides, it represents a badly needed leap forward in regulation, said Carol Tucker Foreman, a distinguished fellow at the Consumer Federation of America and former Agriculture Department food safety official.

The most important thing is to modernize the underlying statutes and clarify authority, Foreman said.

"If you brought [food regulators from the FDA and the USDA] together now, you'd just have a terrible mess," Foreman said.

It's a jumble that has been compounded by decades of ad hoc fixes as new food concerns arose. Divided oversight dates to the days of "The Jungle," Upton Sinclair's 1906 fictionalized account of the dismal, unsanitary conditions in Chicago slaughterhouses, which caused a massive public outcry and led to federal investigations of the meatpacking industry.

The book, which first was serialized in 1905, increased pressure on Washington to deal with food safety, and in response Congress passed two laws.

The Pure Food and Drug Act was designed to fix problems with adulterated food and drug products, such as so-called elixirs peddled as miracle cures. Responsibility for enforcing the law was assigned to the USDA's Bureau of Chemistry, which later was spun off and became the FDA.

The Meat Inspection Act also gave enforcement duties to the USDA because the agency had staff veterinarians capable of dealing with sick animals and other livestock problems. Since then, food production has become globalized and vastly more complex, and the FDA's powers and funding, in particular, have not kept up.

The food safety bill now in the Senate aims to transform the FDA from an agency that reacts to food-borne illness outbreaks to one that heads them off by setting new quality standards, increasing inspections and requiring better record-keeping by food producers. It also would give the FDA the power to order food recalls on its own instead of relying on cooperation from industry.

The bill enjoys widespread support from food safety groups, consumer advocates and food producers, some of them stung by the expense of major recalls resulting from federal regulators' inability to prevent outbreaks.